Gray recently fielded a host of my questions. The full interview is after the jump — and I recommend giving it a read because Gray’s perspective is quite valuable — but I also want to call out three important points he made:

The level of interactivity and multimedia included in a digital edition must be decided on a case-by-case basis. “There were a whole lot of ideas for interactivity that we didn’t put in, because they didn’t pass the test of actually making the book better,” Gray said, discussing the iPad edition of “The Elements.”

Truly useful interactivity requires skill sets beyond those commonly found in publishing companies: videography, audio, programming, etc. If you want to produce a great ebook (or app), you need to bring in people who can make that happen. “Programmers need to be treated as top talent, just like authors,” Gray said.

Gift giving is directly related to the physical nature of print books. “A gift code for a copy of the ebook is really just not the same thing,” he said.

You’ll find the full interview and lots more insight below.

“The Elements” is available as both a print book and an ebook. Which came first?

Theodore Gray: It’s more accurate to say that both the print and ebook versions started out as a website. I have been collecting and photographing these objects since 2002, and all the photographs in the book are also online (along with a couple thousand more).

There was a fairly slippery slope after I started photographing the objects and putting them on my website. First Popular Science asked me to write a monthly column, then I decided to publish a periodic table poster, and pretty soon (2008) I decided I was ready to write a whole book about the elements. The book came out in print form first only because in 2009 when it was published there did not exist any platform on which it was possible to publish an ebook of the kind I wanted to and make any money on it.

Do you see the iPad and iPhone editions as completely separate products, or are they extensions of the book?

TG: Both are extensions of the same raw material. They have all the same text and mostly the same objects. But they are completely different layouts and navigation because the different screen sizes don’t really allow it to work the same way in both places.

“The Elements” has been held up as an example of how book-like experiences can be transitioned and extended into a digital environment. What are the key features in “The Elements” that facilitate this transition?

TG: “The Elements” is a book about objects: Physical things that I have in my office and you don’t. This fact drives everything about the design of this particular ebook. Because the objects I talk about are three-dimension objects that don’t really do much other than sit there, I thought the best thing I could do to communicate their nature was to let you turn them around like you would if you were holding them in your hand, and see them in stereo 3D, as you would if you had them in front of you.

So in the case of “The Elements,” the key interactive feature is real-time rotatable 3D objects that can optionally be displayed in stereo 3D. But ebooks about different kinds of topics might want to contain completely different kinds of interactivity.

What skills — or people with those skills — must be incorporated into the editorial process to produce something like the iPad / iPhone editions?

TG: Specifically in the case of “The Elements,” the skills required were writing, commercial-style stills photography, Objective-C programming, and a whole, whole lot of Mathematica programming to create the design and layout tool and image processing software we used to create all the media assets that went into the ebook.

Other ebooks might well require different skills. My next one, for example, is going to include a lot more video, so we’re gearing up to produce high-grade stereo 3D video. That’s one of the challenges in producing interesting ebooks: You need a wider range of skills than to produce a conventional print book.

When it comes to interactivity and multimedia, what mistakes are traditional book publishers making?

TG: It will be interesting to see all the mistakes they make over the next year or two. So far the two mistakes I’ve seen are (1) not understanding that programmers need to be treated as top talent, just like authors and (2) mistaking gimmicks for meaningful interactivity.

Just adding something that rattles around on the page does not mean you have enhanced the reading experience or added to the user’s understanding of the subject. The interactivity in “The Elements” is very minimalist, and this is one of its strengths. There were a whole lot of ideas for interactivity that we didn’t put in, because they didn’t pass the test of actually making the book better.

“The Elements” is sold as an app rather than as an ebook. Will the line between “app” and “ebook” blur?

TG: I think it’s confusing and un-Apple-like for there to be both a bookstore and a books category in the App Store. These two places exist for purely technical reasons, and not very good ones at that. Hopefully at some point Apple will fix this. In the mean time, all the interesting ebooks will need to go in the App Store, because the iBookstore is not able to handle them.

TG: We decided about a week before the iPad launch that “The Elements” was going to get people’s attention, and that it might be fun to see if anyone was interested in working with us to create new ebooks. The answer is a resounding yes.

Do you define Touch Press as a book publishing company?

TG: We are an ebook publishing company that works with partners from many industries, including traditional print publishing, television, film, music, and interactive media.

What titles are you developing?

TG: We are developing quite a few titles with multiple partners, but are not at liberty to give details just yet. The only thing I can say is that my own next book, which will of course be published by Touch Press, will be called “Reactions,” and will come out, with luck, in 2012. It’s going to show what happens when you bring the elements together and let them have fun.

How do you see publishing changing over the next 5-10 years?

TG: I think it’s quite possible that paper will continue to exist as a publishing medium for quite a while, primarily because of the advantages it has for gift giving and other situations where you need to give (or sell very cheaply) a completely self-contained object. This didn’t save physical media for music very long because no matter what, you always had to have some kind of player device, and if you’re going to have a player it might as well be an MP3 player that holds thousands of songs. And it didn’t save newspapers for much longer because the need for repeated daily distribution makes physical media entirely unsuitable.

But with books it is possible to have a completely self-contained physical object that you can hand to anyone anywhere in the world, and that will have lasting value to them over a period of many years. In a situation like that, a book is more like a vase or a clock-radio: The physical nature of the gift is as important as what specifically it is. And gift giving is a huge market.

On my recent trip to Japan and China, on which I talked to many people about my ebook, I didn’t hand out a single copy of the ebook. Instead I took several dozen copies of my print book to give away to reporters and publishing executives, who were always delighted to get such a lovely physical object. A gift code for a copy of the ebook is really just not the same thing.

But for textbooks and other kinds of books that are not given as gifts, I could well imagine a cliff not unlike the MP3 cliff music faced. A massive, nationwide switch to electronic textbooks from one year to the next. The situation with print textbooks is ridiculous on several levels, just as the notion of physical media to distribute music became ridiculous to many people over a very short time span. Once students have the option of carrying one small, lightweight device that costs no more than a single print textbook did the year before, they are not going to waste any time switching.